The invention relates to an adjusting mechanism for a vehicle seat back.
Typically, a vehicle seat back can be adjusted by being tilted forwardly or rearwardly and is held in selected positions of adjustment by a brake mechanism. The brake mechanism can be released by manual rotation of a brake-release hand wheel (or by a hand lever). The hand wheel is rotatable selectively in clockwise and counter clockwise directions. When the hand wheel is rotated in the clockwise direction, the seat back can be adjusted in a first direction but remains braked against adjustment in the second (opposite) direction. When the hand wheel is rotated in the counter clockwise direction, the seat back can be adjusted in the second direction but is braked against adjustment in the first direction. There is no position of the hand wheel which provides the user with the option of adjusting the seat back in either the first direction or second direction.
The brake mechanism acts upon a shaft which is operably connected to the seat back such that when the shaft is braked, the seat back cannot be adjusted; when the shaft is free-running, the seat back can be adjusted.
In particular, and as disclosed in EP 0 370 502, free-running brakes operate in such a way, for example, that they fix an adjustment hub in a median position and have a hand wheel for releasing the adjustment hub for free rotation in either of two opposing directions. The braking part comprises two braking areas positioned about the same axis which can be swivelled relative to each other by a given swivelling angle, whereby the one area includes two spring elements which press two roller bodies into the locked position between clamping surfaces of the braking area and the opposite circular cylindrical surface of the housing, and the second brake area has a pressure surface lying in the median position at a small distance from the roller bodies which release a clamping body from the clamped position when turned in either of the two directions.
Furthermore, a brake is disclosed in German Document 91 01 110-U1 for the transmission of a rotational movement in both rotational directions, whereby the brake is provided with a free-running hub and a catch of the kind that enables the brake to be freely rotated in both rotational directions by the force from the driving gear to the main drive pinion and locks with the reversal of the force. This is useful for seats with free-running which work in both rotational directions. The brake comprises a pair of clamping bodies which are pressed into their locked position on a wedge surface by springy elastic elements and pushed out of their locked position by an actuator when an actuator is displaced. The actuator is a drive wheel which preferably meshes eccentrically with an inner toothing on the part to be adjusted, with a high gear ratio, and the driving gear as well as the main drive wheel are positioned or sit on a common hub. The clamping body of the free-running hub on one hand runs on a frame-mounted hub and the slated surfaces for clamping the clamping bodies of the free-running hub are formed on the inner surface of a ring surrounding the hub, which is connected with the surrounding main pinion wheel and provided with projections. The projections engage in the openings on the driving wheel for displacing the clamping bodies from their clamped position. In this kind of free-running brake or gear for which the configuration revealed above is only an example, the hub can be made free running in one direction or the other, depending upon the manner of actuation of the actuator, but the actuator cannot enable the hub to be free-running in both directions. That is, there is no position of the hand wheel in which the seat back can be selectively adjusted in either of two directions.
The invention has the task of creating an adjusting mechanism for a vehicle seat back in which a brake can be locked in both directions, or released in both directions by means of a simplified mechanism which possesses advantageous properties of free-running brakes known to this point.
The invention also has an object to provide an effective actuator for releasing the brake.